How to Dilute Roundup


Roundup is a nonselective herbicide used to kill weeds, or other unwanted plants, in lawns and gardens. The term nonselective means Roundup will kill any plant it comes in contact with, so caution must be taken to only spray Roundup on plants you wish to kill. Apply Roundup on a day with little to no wind, as the spray can be carried by gusts of wind onto plants you do not wish to kill.

Step 1

Inspect the hand-held sprayer for dirt or debris. Rinse out the sprayer if necessary.

Step 2

Fill hand-held sprayer with 1 gallon of clean water.

Step 3

Pour recommended amount of Roundup solution into the hand-held sprayer. A 0.5 percent solution requires the addition of 0.7 oz of Roundup solution, while a one percent solution requires the addition of 1.3 oz of Roundup solution. Add the Roundup to the sprayer when pouring the last few ounces of water into the sprayer, to begin the mixing process.

Step 4

Add a defoaming agent, if desired, to the water and Roundup solution. This will lessen the foaming action that occurs during both mixing and spraying the solution.

Step 5

Mix the water and Roundup, slowly, by hand. Do not use mechanical mixers, which will only encourage foaming.

Tips and Warnings

  • Never apply Roundup through an irrigation system. Always use clean water when diluting Roundup. Dirty water can reduce the effectiveness of Roundup.

Things You'll Need

  • Hand-held sprayer
  • Defoaming agent (optional)


  • University of Montana: Roundup Label

Who Can Help

  • Weed Management in Home Lawns
Keywords: diluting Roundup, mixing Roundup, water Roundup ratio

About this Author

Sophia Darby is a former professional hairstylist who has spent the last six years writing hair-related articles for both online and print publications. Her work has appeared in Celebrity Hairstyles Magazine, as well as multiple websites.